Passive House: High Performance Houses for a Warmer Future

Imagine you're building a home. What if you could design it so your electric bill was next to nothing, but it would cost you 10 percent more upfront? Would it be worth it to you? 

For Jennifer and Sloan Ritchie of Seattle, Washington, the answer was a resounding, "Yes!" 

"Sloan is a builder and he believes in the reality of climate change and understands how buildings contribute to that. He was looking for something that focused on energy efficiency and was aligned with his vision for creating really high-performance housing," says Jennifer Ritchie. Heating and cooling can account for as much as 60 percent of a building's electrical load. 

The couple knew they eventually wanted to build a dwelling that matched their sustainability values. They found out about Passive House - buildings that are well insulated and low cost to maintain - and when an infill lot in Seattle's Madison Park neighbourhood fell into their laps in 2012, it was the perfect opportunity. Or so they thought. 

"Right out of the gate, we decided we were going to build a Passive House," says Ritchie. But there were obstacles. 

"One of the basic principles of Passive House is to design the building so it gets as much free heat from the sun as possible, and then holds onto that heat for as long as possible," says Jordan Goldman, a Passive House consultant with Zero Energy Design in Brooklyn, NY. Averaging only 58 days of sunshine per year, Seattle isn't exactly ideal. 

There were also problems with where the lot was situated.  "Everyone we talked to said this was the worst lot possible to build a Passive House because it was surrounded by tall houses. Getting the southern exposure we needed was going to be a challenge," says Ritchie. 

In addition, they wanted the modern three-story to be bright. "We're a family of four and we wanted lots of light. The challenging thing with infill lots is they can be really dark," says Ritchie. This proved to be the biggest obstacle for their designers, Marie Ljubojevic and Lauren McCunney at NK Architects in Seattle, WA. 

After designs were created, NK applied the Passive House model, but they had to keep tweaking it. "I don't know how many times we had to change the window sizes, just to be able to capture enough energy and keep it in," says Ritchie. But they persisted. 

The family has since spent a year in their new domicile, called Park Passive. Last winter was unusually cold for more temperate Seattle but Ritchie, who hates the cold, says she was comfortable. "On the day the newspaper said it was the coldest day on record, it was 70 in our house. And we didn't run the heater." 

The couple estimates the cost of building to Passive House standards, was about 5 percent higher than conventional methods but says it costs a lot less to run than their old home. "In our old house, in the wintertime we spent $250 a month on heat and electricity. Now, our bill is about $30 a month year round, and this house is twice the size," says Ritchie. 

In her book American Passive House Developments, author Mary James describes Passive House as an approach that allows architects "to design superinsulated, very airtight buildings that require minimal energy use to heat, cool, dehumidify, and ventilate." Such structures achieve the ultimate energy independence - freedom from fossil fuels - while maintaining comfort and low operational costs.  

To understand Passive House strategy, it's helpful to understand the concept of a building envelope. "In effect, it is the structure that protects you from the outside environment and keeps you comfortable inside. In a colder environment, you heat the interior; in a warmer environment, you cool it. Insulation helps prevent warm or cool air from leaking out," says Goldman. 

If you've ever felt a draft next to a window or door, then you've experienced a leak in the building's envelope. 

[Passive houses] achieve the ultimate energy independence - freedom from fossil fuels - while maintaining comfort and low operational costs.

According to the National Institute of Building Sciences, the first building envelope was probably a cave. Building science quickly evolved to wooden, stone and metal structures, and today, a lot of construction uses glass. 

In order to prevent leaks in those structures, building analyses look at how the foundation, floors, walls and roof are built and insulated. The Passive House model minimizes leaks and maximizes heating and cooling retention in all four areas. 

Germany was an early adopter of Passive House concepts (called PassivHaus) in the mid-1990s, but it is relatively new to North America. There are only an estimated 40 to 50 certified Passive Houses in the US, which often leads to claims of firsts, such as first Passive House in Brooklyn and first Passive House in New York. Likewise, Park Passive is the first Passive House in Seattle. 

Contrary to what the name implies, Passive House doesn't just apply to houses. Around the country, projects have included studios and art centers, and Hollis Montessori School is the Nation's first certified Passive School. 

Located in southern New Hampshire, where winter temperatures frequently dip below freezing, Hollis recently underwent construction of a new schoolhouse and "now uses 85 to 90 percent less energy than other similar schools in the northeast," says Goldman. 

The school was tested for leaks, using a method called a "blower door test," and according to Frank Grossman, the school board member who championed the project, "We were ready to go find all the leaks but nothing needed to be done." In fact, Hollis performed so well, Goldman says it's one of the most airtight structures in the country. 

The Passive House concept proved itself toward the end of construction at Hollis, according to Goldman. "After we got the building insulated we were working without the heat on in the middle of winter, on a cold day and the building maintained a temperature of 67 degrees. We had small heaters and we didn't even need them, which I thought was really cool."

Hollis too faced increased costs of about 10 percent. Grossman says the board was "supportive but cautious," and they never calculated a payback period "...because of what we wanted to accomplish. We want less of a [carbon] footprint and an environmentally respectful building, and the price was reasonable to do that," says Grossman. 

The Ritchies wanted to take advantage of their environmentally respectful abode by holding open houses to promote Passive House. Initially, they planned to live in Park Passive for a year, show it off, and then sell it. Now Ritchie says she doesn't want to move. 

"In the old house, Sloan was pretty chintzy about the heat. At night, he would turn it down to 65 degrees and then tell everybody to wear a lot of clothes." Now, Ritchie says she wears shorts and flip-flops in the middle of winter. "I don't want to sell it, because I love it, she says. "I can't see ever living in a drafty house again."


All photos from Jennifer and Sloan Ritchie.